I don't think there's any need to buy a lifetime supply of CI-4 oil. CJ-4 may not be quite as "good" (at least from my perspective) as CI-4, but maybe the phosphorous limitation is offset by the higher oxidation resistance. There are so many tradeoffs and so many different operating conditions, even the experts who deal with these issues everyday can't reach a consensus.

When CJ-4 hits the market I expect all the CI-4s to be discontinued. We'll have to wait and see. For sure CJ-4 will still be better for older spark ignition engines that don't have "roller everything" (like modern engines), than SM oil, and there are enough older diesels using high sulphur fuel, especially off-road, in operation that maybe some manufacturers will continue to offer CI-4 if the demand is there. I will use it as long as its conveniently available. Then I'll switch my cars to CJ-4.

CJ-4 may not be as good as CI-4 in diesels that use high suphur fuels, but that's not an issue in SI engines since gasolines are already very low sulphur, but I don't like the reduction in phosphorous, which will dictate less ZDDP, however less means there is less risk of SI catalyst damage.

It's all about many different tradeoffs and probably not worth losing any sleep over.

Duke